Muscle metabolism during exercise in children with Juvenile Dermatomyositis and the relationship with inflammation

Juvenile dermatomyositis is an autoimmune disease, which leads to inflammation
of muscles and skin. These inflammations cause a reduction of (especially) the
muscle groups around the shoulder- and pelvic girdle, which lead to a decreased
exercise tolerance and independency in general daily necessity of life. The
treatment consists of (combinations of) immunosuppressive medication. Former
studies show that, despite intensive immunosuppressive therapy, inadequate
recovery of the exercise tolerance occur.[Takken, 2005] At the moment, it is
unclear whether active exercise of muscles contribute to a faster recovery and
preservation of muscle power on the long term. Certain forms of exercise can
have an immune-modulating effect [Wiesinger 2001, Alexanderson, 2005]. However
it is not know whether there is a difference in the effects of physical
training on recovery of the muscles in the active phase or remission phase of
the disease.

To get insight in the aforementioned, it is desirable to determine the effect
of exercise upon muscle level.
For this purpose, until now indirect parameters (lab-testing, exercise testing,
and imaging such as MRI) or invasive methods (such as muscle biopsy) were used
after exercise. 'Fosfor kernspin resonantie spectroscopie' (31P MRS) is an
alternative non-invasive method to measure the muscle energetics during
exercise. [Prompers 2007, Jeneson 2004] Improvement in the energetics during an
exercise test as a result of training can further be used as a testing
criterion for optimizing the training protocol.

The here mentioned study concerns a pilot study in which 31P MRS will be
combined with a exercise pattern for the first time. This exercise pattern is
comparable with daily exercise in the clinical setting (cycling). The
Biomedical NMR research group in Eindhoven has developed a unique measurement
facility for this study, which will be used to determine the muscle energetics
in the leg muscle during exercise on the recumbent bicycle in children with
JDM. The results will be compared with those of the healthy age- and gender
matched subjects. The study populations consist of 5 patients between 12 and 18
years of age with diagnosed and treated juvenile dermatomyositis, in a stable
phase. Results will be compared with already known data of healthy adults
obtained in Eindhoven, as well new data to be obtained from age and
gender-matched children.

In this pilot study the effects of exercise on muscle energetics in the
proximal muscle groups of the legs with patients with Juvenile Dermatomyositis
will be cross-sectional studied. This will be done with an exercise test using
a recumbent bicycle- ergometer formation in a low-field MRscanner

Five patients between 12 and 18 years of age with a diagnosed and treated
juvenile dermatomyositis (in clinical remission) will execute a maximal
exercise test (staircase protocol) once-only in a low-field (1.5 T) MR scanner
during 20 minutes and an once-only without a MRscanner.

The burden is an once-only measurement in a low-field (1.5 T) MR scanner during
20 minutes and an once-only measurement without a MRscanner.